Correct PPTP server firewall rules chain.

[tomato/davidwu.git] / release / src / router / hotplug2 / hotplug2.c

/*****************************************************************************\
*  _  _       _          _              ___                                   *
* | || | ___ | |_  _ __ | | _  _  __ _ |_  )                                  *
* | __ |/ _ \|  _|| '_ \| || || |/ _` | / /                                   *
* |_||_|\___/ \__|| .__/|_| \_,_|\__, |/___|                                  *
*                 |_|            |___/                                        *
\*****************************************************************************/

#define _GNU_SOURCE

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <linux/types.h>
#include <linux/netlink.h>
#include <poll.h>

#include "mem_utils.h"
#include "filemap_utils.h"
#include "hotplug2.h"
#include "hotplug2_utils.h"
#include "rules.h"
#include "childlist.h"

#define TERMCONDITION (persistent == 0 && \
                                        coldplug_p == FORK_FINISHED && \
                                        child == NULL && \
                                        highest_seqnum == get_kernel_seqnum())

/*
 * These variables are accessed from throughout the code.
 *
 * TODO: Move this into a hotplug2_t-like variable.
 */
event_seqnum_t highest_seqnum = 0;
pid_t coldplug_p;
int coldplug = 1;
int persistent = 0;
int override = 0;
int max_child_c = 20;
int dumb = 0;
int terminate = 0;
int child_c;
struct hotplug2_child_t *child;
int netlink_socket;

char *modprobe_command = NULL;

/**
 * Release all memory associated with an uevent read from kernel. The given
 * pointer is no longer valid, as it gets freed as well.
 *
 * @1 The event that is to be freed.
 *
 * Returns: void
 */
inline void free_hotplug2_event(struct hotplug2_event_t *event) {
        int i;
        
        for (i = 0; i < event->env_vars_c; i++) {
                free(event->env_vars[i].key);
                free(event->env_vars[i].value);
        }
        free(event->env_vars);
        free(event->plain);
        free(event);
}

/**
 * A trivial function determining the action that the uevent.
 *
 * @1 String containing the action name (null-terminated).
 *
 * Returns: Macro of the given action
 */
inline int get_hotplug2_event_action(char *action) {
        if (!strcmp(action, "add"))
                return ACTION_ADD;
        
        if (!strcmp(action, "remove"))
                return ACTION_REMOVE;
        
        return ACTION_UNKNOWN;
}

/**
 * Looks up a value according to the given key.
 *
 * @1 A hotplug event structure
 * @2 Key for lookup
 *
 * Returns: The value of the key or NULL if no such key found
 */
char *get_hotplug2_value_by_key(struct hotplug2_event_t *event, char *key) {
        int i;
        
        for (i = 0; i < event->env_vars_c; i++) {
                if (!strcmp(event->env_vars[i].key, key))
                        return event->env_vars[i].value;
        }

        return NULL;
}

/**
 * Appends a key-value pair described by the second argument to the
 * hotplug event.
 *
 * @1 A hotplug event structure
 * @1 An item in format "key=value" to be appended
 *
 * Returns: 0 if success, -1 if the string is malformed
 */
int add_hotplug2_event_env(struct hotplug2_event_t *event, char *item) {
        char *ptr, *tmp;
        
        ptr = strchr(item, '=');
        if (ptr == NULL)
                return -1;
        
        *ptr='\0';
        
        event->env_vars_c++;
        event->env_vars = xrealloc(event->env_vars, sizeof(struct env_var_t) * event->env_vars_c);
        event->env_vars[event->env_vars_c - 1].key = strdup(item);
        event->env_vars[event->env_vars_c - 1].value = strdup(ptr + 1);
        
        /*
         * Variables not generated by kernel but demanded nonetheless...
         *
         * TODO: Split this to a different function
         */
        if (!strcmp(item, "DEVPATH")) {
                event->env_vars_c++;
                event->env_vars = xrealloc(event->env_vars, sizeof(struct env_var_t) * event->env_vars_c);
                event->env_vars[event->env_vars_c - 1].key = strdup("DEVICENAME");
                tmp = strdup(ptr + 1);
                event->env_vars[event->env_vars_c - 1].value = strdup(basename(tmp));
                free(tmp);
        }
        
        *ptr='=';
        
        return 0;
}

/**
 * Duplicates all allocated memory of a source hotplug event
 * and returns a new hotplug event, an identical copy of the
 * source event.
 *
 * @1 Source hotplug event structure
 *
 * Returns: A copy of the source event structure
 */
inline struct hotplug2_event_t *dup_hotplug2_event(struct hotplug2_event_t *src) {
        struct hotplug2_event_t *dest;
        int i;
        
        dest = xmalloc(sizeof(struct hotplug2_event_t));
        dest->action = src->action;
        dest->env_vars_c = src->env_vars_c;
        dest->env_vars = xmalloc(sizeof(struct env_var_t) * dest->env_vars_c);
        dest->plain_s = src->plain_s;
        dest->plain = xmalloc(dest->plain_s);
        memcpy(dest->plain, src->plain, dest->plain_s);
        
        for (i = 0; i < src->env_vars_c; i++) {
                dest->env_vars[i].key = strdup(src->env_vars[i].key);
                dest->env_vars[i].value = strdup(src->env_vars[i].value);
        }
        
        return dest;
}

/**
 * Parses a string into a hotplug event structurs.
 *
 * @1 The event string (not null terminated)
 * @2 The size of the event string
 *
 * Returns: A new event structure
 */
inline struct hotplug2_event_t *get_hotplug2_event(char *event_str, int size) {
        char *ptr;
        struct hotplug2_event_t *event;
        int skip;
        
        ptr = strchr(event_str, '@');
        if (ptr == NULL) {
                return NULL;
        }
        *ptr='\0';
        
        event = xmalloc(sizeof(struct hotplug2_event_t));
        event->action = get_hotplug2_event_action(event_str);
        event->env_vars_c = 0;
        event->env_vars = NULL;
        event->plain_s = size;
        event->plain = xmalloc(size);
        memcpy(event->plain, event_str, size);
        
        skip = ++ptr - event_str;
        size -= skip;
        
        while (size > 0) {
                add_hotplug2_event_env(event, ptr);
                skip = strlen(ptr);
                ptr += skip + 1;
                size -= skip + 1;
        }
        
        return event;
}

/**
 * Evaluates an argument into a true/false value.
 *
 * @1 argument
 * @2 argument flag
 * @3 pointer to output value
 *
 * Returns: 0 if success, -1 otherwise
 */
int get_bool_opt(char *argv, char *name, int *value) {
        int rv = -1;
        
        if (!strncmp(argv, "--no-", 5)) {
                rv = 0;
                argv+=5;
        }
        
        if (!strncmp(argv, "--", 2)) {
                rv = 1;
                argv+=2;
        }
        
        if (rv == -1)
                return -1;
        
        if (!strcmp(argv, name)) {
                *value = rv;
                return 0;
        } else {
                return -1;
        }
}

/**
 * Performs a cleanup; closes uevent socket, resets signal
 * handlers, waits for all the children.
 *
 * Returns: void
 */
void cleanup() {
        pid_t p;
        
        close(netlink_socket);
        
        signal(SIGUSR1, SIG_DFL);
        signal(SIGINT, SIG_DFL);
        signal(SIGCHLD, SIG_DFL);
        
        INFO("cleanup", "Waiting for children.");
        /* Wait for our possible children... */
        while ((p = wait(NULL)) != -1)
                DBG("cleanup", "pid: %d.", p);
        INFO("cleanup", "All children terminated.");
}

/**
 * Handles all signals.
 *
 * @1 Signal identifier
 *
 * Returns: void
 */
void sighandler(int sig) {
        pid_t p;
        
        switch (sig) {
                /*
                 * SIGINT simply tells that yes, we caught the signal, and 
                 * exits.
                 */
                case SIGINT:
                        INFO("sighandler", "Obtained SIGINT, quitting.");
                        cleanup();
                        exit(0);
                        break;
                
                /*
                 * SIGUSR1 is handled so that if we have turned off persistency
                 * and have processed all events, we quit.
                 */
                case SIGUSR1:
                        persistent = !persistent;
                        INFO("sighandler", "Changed persistency to: %s", persistent ? "yes" : "no");
                        if (TERMCONDITION) {
                                INFO("sighandler", "No more events to be processed, quitting.");
                                cleanup();
                                exit(0);
                        }
                        break;
                
                /*
                 * SIGCHLD helps us to figure out when a child died and
                 * what kind of child it was. It may also invoke termination.
                 */
                case SIGCHLD:
                        while (1) {
                                p = waitpid (WAIT_ANY, NULL, WNOHANG);
                                if (p <= 0)
                                        break;
                                
                                DBG("sighandler", "caught pid: %d.", p);
                                if (p == coldplug_p) {
                                        DBG("sighandler", "coldplug_p: %d.", coldplug_p);
                                        coldplug_p = FORK_FINISHED;
                                } else {
                                        child = remove_child_by_pid(child, p, NULL, &child_c);
                                }
                                
                                DBG("sighandler", "child_c: %d, child: %p, highest_seqnum: %lld, cur_seqnum: %lld, coldplug_p: %d.\n", child_c, child, highest_seqnum, get_kernel_seqnum(), coldplug_p);
                        }
                        
                        if (TERMCONDITION) {
                                INFO("sighandler", "No more events to be processed, quitting.");
                                cleanup();
                                exit(0);
                        }
                        break;
        }
}

#ifdef HAVE_RULES
/**
 * Execute all rules for this particular event.
 *
 * @1 Hotplug event structure
 * @2 Rules structure, containing array of rules
 *
 * Returns: void
 */
void perform_action(struct hotplug2_event_t *event, struct rules_t *rules) {
        int i, rv;
        
        for (i = 0; i < rules->rules_c; i++) {
                rv = rule_execute(event, &rules->rules[i]);
                if (rv == -1)
                        break;
        }
        
        free_hotplug2_event(event);
}

/**
 * Iterates through all rules, and performs an AND between all flags that
 * would apply during execution (ie. all rules that have conditions matching
 * the hotplug event).
 *
 * @1 Hotplug event structure
 * @2 Rules structure, containing array of rules
 *
 * Returns: Flags that apply to all matching rules
 */
int flags_eval(struct hotplug2_event_t *event, struct rules_t *rules) {
        int flags = FLAG_ALL;
        int match = 0;
        int i, j;

        for (i = 0; i < rules->rules_c; i++) {
                match = 1;

                for (j = 0; j < rules->rules[i].conditions_c; j++) {
                        if (rule_condition_eval(event, &rules->rules[i].conditions[j]) != EVAL_MATCH) {
                                match = 0;
                                break;
                        }
                }

                /*
                 * Logical AND between flags we've got already and
                 * those we're adding.
                 */
                if (match) {
                        rule_flags(&rules->rules[i]);
                        flags &= rules->rules[i].flags;
                }
        }

        /*
         * A little trick; if no rule matched, we return FLAG_ALL
         * and have it skipped completely.
         */

        return flags;
}
#else
#define perform_action(event, rules)
#endif

/**
 * Blindly modprobe the modalias, nothing more.
 *
 * @1 Hotplug event structure
 * @2 Modalias to be loaded
 *
 * Returns: void
 */
void perform_dumb_action(struct hotplug2_event_t *event, char *modalias) {
        free_hotplug2_event(event);
        execl(modprobe_command, modprobe_command, "-q", modalias, NULL);
}

/**
 * Attempt to figure out whether our modprobe command can handle modalias.
 * If not, use our own wrapper.
 *
 * Returns: 0 if success, -1 otherwise
 */
int get_modprobe_command() {
        pid_t p;
        int fds[2];
        char buf[18];
        FILE *fp;
        
        pipe(fds);
        
        p = fork();
        
        switch (p) {
                case -1:
                        ERROR("modprobe_command","Unable to fork.");
                        return -1;
                        break;
                
                case 0:
                        close(fds[0]);
                        close(2);
                        dup2(fds[1], 1);
                
                        execlp("/sbin/modprobe", "/sbin/modprobe", "--version", NULL);
                        exit(1);
                        break;
        
                default:
                        close(fds[1]);
                        fp = fdopen(fds[0], "r");
                        fread(buf, 1, 17, fp);
                        buf[17]='\0';
                
                        /* 
                         * module-init-tools can handle aliases.
                         * If we do not have a match, we use hotplug2-depwrap,
                         * even though our modprobe can do fnmatch aliases,
                         * which is the case of eg. busybox.
                         */
                        if (!strcmp(buf, "module-init-tools")) {
                                modprobe_command = "/sbin/modprobe";
                        } else {
                                modprobe_command = "/sbin/hotplug2-depwrap";
                        }
                        fclose(fp);
                        waitpid(p, NULL, 0);
                        break;
        }
        return 0;
}

int main(int argc, char *argv[]) {
        /*
         * TODO, cleanup
         */
        static char buffer[UEVENT_BUFFER_SIZE+512];
        struct hotplug2_event_t *tmpevent;
        char *modalias, *seqnum;
        event_seqnum_t cur_seqnum;
        pid_t p;
        int recv_errno;
        int size;
        int rv = 0;
        int i;
        unsigned int flags;
        char *coldplug_command = NULL;
        char *rules_file = HOTPLUG2_RULE_PATH;
        sigset_t block_mask;
        struct pollfd msg_poll;

        struct hotplug2_event_t *backlog = NULL;
        struct hotplug2_event_t *backlog_tail = NULL;
        int n_backlog = 0;
        
        struct rules_t *rules = NULL;
        struct filemap_t filemap;

        struct options_t bool_options[] = {
                {"persistent", &persistent},
                {"coldplug", &coldplug},
                {"udevtrigger", &coldplug},     /* compatibility */
                {"override", &override},
#ifdef HAVE_RULES
                {"dumb", &dumb},
#endif
                {NULL, NULL}
        };
        
        /*
         * We parse all the options...
         */
        for (argc--; argc > 0; argc--) {
                argv++;
                /*
                 * TODO, cleanup
                 */
                for (i = 0; bool_options[i].name != NULL; i++) {
                        if (!get_bool_opt(*argv, bool_options[i].name, bool_options[i].value)) {
                                /*
                                 * Bool options are --option or --no-options. If we handled
                                 * it, quit iterating.
                                 */
                                break;
                        } else {
                                if (!strcmp(*argv, "--max-children")) {
                                        argv++;
                                        argc--;
                                        if (argc <= 0)
                                                break;
                                        
                                        max_child_c = strtol(*argv, NULL, 0);
                                } else if (!strcmp(*argv, "--set-coldplug-cmd")) {
                                        argv++;
                                        argc--;
                                        if (argc <= 0)
                                                break;
                                        
                                        coldplug_command = *argv;
                                } else if (!strcmp(*argv, "--set-modprobe-cmd")) {
                                        argv++;
                                        argc--;
                                        if (argc <= 0)
                                                break;
                                        
                                        modprobe_command = *argv;
                                } else if (!strcmp(*argv, "--set-rules-file")) {
                                        argv++;
                                        argc--;
                                        if (argc <= 0)
                                                break;
                                        
                                        rules_file = *argv;
                                }
                        }
                }
        }
        
#ifndef HAVE_RULES
        /*
         * We don't use rules, so we use dumb mode only.
         */
        dumb = 1;
#else
        /*
         * We're not in dumb mode, parse the rules. If we fail,
         * faillback to dumb mode.
         */
        if (!dumb) {
                if (map_file(rules_file, &filemap)) {
                        ERROR("rules parse","Unable to open/mmap rules file.");
                        dumb = 1;
                        goto end_rules;
                }
                
                rules = rules_from_config((char*)(filemap.map), NULL);
                if (rules == NULL) {
                        ERROR("rules parse","Unable to parse rules file.");
                        dumb = 1;
                }

                unmap_file(&filemap);
                
end_rules:      
                if (dumb == 1)
                        ERROR("rules parse","Parsing rules failed, switching to dumb mode.");
        } else
#endif
        /*
         * No modprobe command specified, let's autodetect it.
         */
        if (!modprobe_command)
        {
                if (get_modprobe_command()) {
                        ERROR("modprobe_command","Unable to autodetect modprobe command.");
                        goto exit;
                }
                DBG("modprobe_command", "Using modprobe: `%s'.", modprobe_command);
        }
        
        /*
         * Open netlink socket to read the uevents
         */
        netlink_socket = init_netlink_socket(NETLINK_BIND);
        msg_poll.fd = netlink_socket;
        msg_poll.events = POLLIN;
        
        if (netlink_socket == -1) {
                ERROR("netlink init","Unable to open netlink socket.");
                goto exit;
        }

        child = NULL;
        child_c = 0;
        
        signal(SIGUSR1, sighandler);
        signal(SIGINT, sighandler);
        signal(SIGCHLD, sighandler);
        
        /*
         * If we desire coldplugging, we initiate it right now.
         */
        if (coldplug) {
                if (coldplug_command == NULL)
                        coldplug_command = UDEVTRIGGER_COMMAND;
                coldplug_p = fork();
                switch (coldplug_p) {
                        case FORK_ERROR:
                                ERROR("coldplug","Coldplug fork failed: %s.", strerror(errno));
                                perror("coldplug fork failed");
                                goto exit;
                                break;
                        case 0:
                                execlp(coldplug_command, coldplug_command, NULL);
                                ERROR("coldplug","Coldplug exec ('%s') failed: %s.", coldplug_command, strerror(errno));
                                goto exit;
                                break;
                }
        } else {
                coldplug_p = FORK_FINISHED;
        }
        
        /*
         * Main loop reading uevents
         */
        while (!terminate) {
                if ((n_backlog > 0) && (child_c < max_child_c)) {
                        /* dequeue backlog message */
                        tmpevent = backlog;
                        backlog = backlog->next;
                        n_backlog--;
                        if (backlog_tail == tmpevent)
                                backlog_tail = NULL;
                } else {
                        /*
                         * Read the uevent packet
                         */
                        if (n_backlog >= HOTPLUG2_MSG_BACKLOG) {
                                usleep(HOTPLUG2_THROTTLE_INTERVAL * 1000);
                                continue;
                        }

                        if ((n_backlog > 0) && (child_c >= max_child_c)) {
                                int fds;
                                msg_poll.revents = 0;
                                fds = poll(&msg_poll, 1, HOTPLUG2_THROTTLE_INTERVAL);
                                if (fds < 0) {
                                        continue;
                                }
                                if (fds == 0)
                                        continue;
                        }
                        size = recv(netlink_socket, &buffer, sizeof(buffer), 0);
                        recv_errno = errno;
                        if (size < 0)
                                continue;
        
                        /*
                         * Parse the event into an event structure
                         */
                        tmpevent = get_hotplug2_event(buffer, size);
                
                        if (tmpevent == NULL) {
                                ERROR("reading events", "Malformed event read (missing action prefix).");
                                continue;
                        }
                }
                
                /*
                 * Look up two important items of the event
                 */
                modalias = get_hotplug2_value_by_key(tmpevent, "MODALIAS");
                seqnum = get_hotplug2_value_by_key(tmpevent, "SEQNUM");

                /*
                 * Seqnum is necessary not to end up in a race with the kernel.
                 */
                if (seqnum == NULL) {
                        free_hotplug2_event(tmpevent);
                        ERROR("reading events", "Malformed event read (missing SEQNUM).");
                        continue;
                }
                
                /*
                 * Maintain seqnum continuity
                 */
                cur_seqnum = strtoull(seqnum, NULL, 0);
                if (cur_seqnum > highest_seqnum)
                        highest_seqnum = cur_seqnum;
                
                /*
                 * If we are in smart mode, we'll always pass. If we're in dumb mode,
                 * we only pass events that have 'add' action and have modalias set.
                 */
                if ((dumb && tmpevent->action == ACTION_ADD && modalias != NULL) || (!dumb)) {
                        /*
                         * Pre-evaluation of the flags
                         */
                        if (!dumb && override) {
                                flags = flags_eval(tmpevent, rules);

                                DBG("flags", "flag returned: %8x", flags);

                                if (flags == FLAG_ALL)
                                        continue;
                        } else {
                                flags = FLAG_UNSET;
                        }

                        /* 
                         * We have more children than we want. Wait until SIGCHLD handler reduces
                         * their numbers.
                         *
                         * Unless, of course, we've specified otherwise and no rules that match
                         * need throttling.
                         */
                        if (!(flags & FLAG_NOTHROTTLE) && (child_c >= max_child_c)) {
                                /* log the packet and process it later */
                                if (backlog_tail)
                                        backlog_tail->next = tmpevent;
                                else
                                        backlog = tmpevent;
                                tmpevent->next = NULL;
                                backlog_tail = tmpevent;
                                n_backlog++;
                                continue;
                        }
                        
                        sigemptyset(&block_mask);
                        sigaddset(&block_mask, SIGCHLD);
                        sigprocmask(SIG_BLOCK, &block_mask, 0);
                        p = fork();
                        switch (p) {
                                case -1:
                                        ERROR("event", "fork failed: %s.", strerror(errno));
                                        break;
                                case 0:
                                        /*
                                         * TODO: We do not have to dup here, or do we?
                                         */
                                        sigprocmask(SIG_UNBLOCK, &block_mask, 0);
                                        signal(SIGCHLD, SIG_DFL);
                                        signal(SIGUSR1, SIG_DFL);
                                        if (!dumb)
                                                perform_action(dup_hotplug2_event(tmpevent), rules);
                                        else
                                                perform_dumb_action(dup_hotplug2_event(tmpevent), modalias);
                                        exit(0);
                                        break;
                                default:
                                        DBG("spawn", "spawning: %d.", p);
                                        child = add_child(child, p, cur_seqnum);
                                        child_c++;
                                        break;
                        }
                        sigprocmask(SIG_UNBLOCK, &block_mask, 0);
                }
                
                free_hotplug2_event(tmpevent);
        }

exit:
        signal(SIGUSR1, SIG_DFL);
        signal(SIGINT, SIG_DFL);
        signal(SIGCHLD, SIG_DFL);
        
        if (!dumb) {
                rules_free(rules);
                free(rules);
        }

        cleanup();
        
        return rv;
}